The peculiarities of the effect of spin-polarized current on the static and dynamical properties of an antiferromagnetic metal

A phenomenological model is developed to describe the effect of a spin-polarized current on the properties of an antiferromagnetic metal. It is shown that the spin-polarized current induced spin torque depends on the antiferromagnetism vector and therefore plays an important role in magnetic dynamics. Analysis of the dynamical equations obtained in this paper indicates that diverse effects similar to those observed in ferromagnets, for example, instability of definite directions and precession of the antiferromagnetic moment around the 'hard' axis, could exist. In contrast to ferromagnets, a spin-polarized current in antiferromagnetic metals influences the spin-wave spectrum and can give rise to parametric resonance and a spin-flop transition. The results obtained are used to interpret the recently observed gigantic magnetoresistance of an antiferromagnetic nature